Humans are born to run

The 2024 Summer Olympics are in full swing. One of the marquee events is of course the marathon, a grueling test of fitness and athleticism. 

When it comes to endurance running, humans are among the very top mammals in their athletic prowess. While we may not be the best sprinters in the animal kingdom, we can run steadily for long distances, even in hot weather. Our locomotor muscles are dominated by slow-twitch, fatigue-resistant fibers and our unique ability to sweat allows our bodies to effectively dissipate heat.

Humans are so good at endurance running, it seems we were born to do it. But why?

A theory of endurance

In 1984, biologist David Carrier proposed the endurance pursuit hypothesis to explain why humans are such good long-distance runners. According to the theory, endurance running traits in humans evolved to allow us to run down large game animals through persistence hunting.

Twenty years later, Carrier’s theory was expanded upon by scientists Dennis Bramble and Daniel Lieberman, who highlighted the physiological traits conducive to endurance running. They proposed that such traits first appeared in the Homo genus nearly 2 million years ago and “may have been instrumental in the evolution of the human body form.”

The endurance pursuit hypothesis, however, isn’t without its skeptics.

“There are two reservations that have always clung to this hypothesis,” said Bruce Winterhalder, professor emeritus in the UC Davis Department of Anthropology and Graduate Group in Ecology. “One is that running is more costly than walking, so based on a simple cost-benefit analysis, it doesn’t look like an efficient way of hunting.”

“And then secondly, we have some examples of contemporary hunter-gatherers practicing endurance pursuits but probably less than a dozen cases,” he said. “For the skeptics, endurance pursuits can’t have been that important to hunting evolution in the Paleolithic if it’s not that important to hunter-gatherers now.”

But in a recent study appearing in Nature Human Behaviour, Winterhalder and paleoanthropologist Eugène Morin, of Trent University, combine mathematical modeling and a multi-year, ethnohistoric investigation of first-hand accounts of endurance pursuits to bolster support for Carrier’s hypothesis.

Sifting through history

According to Winterhalder, the recent availability of thousands of digitized accounts written by explorers, missionaries and officials combined with analytical software capable of sifting through them was key to uncovering examples of endurance pursuits throughout history.

“We have software that allows us to search for information that dwarfs what we could do if we were trying to read through all the possible sources ourselves,” Winterhalder said.

Thanks to this technology, Winterhalder and Morin uncovered 391 descriptions of hunts, dating from 1527 through the early 20th century, that matched endurance pursuit tactics. Accounts originated from 272 locations around the world, which suggests that endurance pursuit hunting was widely practiced and occurred in diverse environments.

Analyzing the data

Across the historical data, endurance pursuits followed a similar trajectory: hunters encounter a prey animal; a pursuit occurs (with the prey animal rapidly outdistancing the hunters); the prey animal pauses to recuperate after exhausting themselves (allowing the slower-paced hunters to catch up); the prey animal flees again; and the cycle repeats until the animal is completely exhausted and overtaken.

Within that common pattern, tactics differed.   

“There are a fair number of cases in which these pursuits are done by teams, by relay. We also have cases where there’s an individual who will climb a hill nearby and use hand signals to indicate where the animal is going, so the person following can take shortcuts and save energy,” Winterhalder said.

This cooperation during endurance pursuit hunting hints at a social element related to running in humans. According to Winterhalder, exhibiting such athletic prowess could have been a way for males to showcase their value among the community, elevating their social status or chances of finding mates.  

In a follow-up study, Winterhalder and Morin plan to further examine female participation in endurance running. While instances of female participation only occurred in about 3-4% of the accounts in the study’s dataset, Winterhalder said that doesn’t necessarily mean females were not good runners.

“In a fair number of cases, we did find that there are festivals, feasts and ritual events that involve running contests,” Winterhalder said. “In cases where we find mentions of rituals or games, the participants generally are women, men and children.”   

It also doesn’t mean that women weren’t involved in hunts as recent research shows “evidence that early women were also hunting.”  

Backing it up with math

Since his graduate student days at Cornell University, Winterhalder has specialized in adapting mathematical models devised by biologists for calculating the value of pursuing game versus the time and energy costs.

For this latest study, Winterhalder and Morin used the models to account for increasing velocity during game pursuits. He and Morin then compared return rates from endurance pursuit hunts to other common foraging methods.

“We found that in contexts like high heat or a substrate that impedes the animal, such as crusted snow, the net return rate of food acquisition from endurance pursuits can match or exceed that of other methods of prey acquisition. The chance of pursuit failure appears to diminish, and exhausted prey are safer to approach. For early humans without ballistic weaponry, these are significant advantages,” Winterhalder said.

Winterhalder hopes the research will generate more interest in the scientific community about the origins of our running gait and, possibly, why some people find the activity to be incredibly satisfying, à la the proverbial “runner’s high.”

“To run long distances, to have an evolved gait that’s uniquely imbued with stamina is unusual in the animal world,” Winterhalder said. “If that inspires you to go for a run, great.”

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